Even when there’s a coronavirus vaccine, it could be another six months before you’re able to take it:

Different vaccines are produced in different ways, and factories are likely to be starting from scratch in ramping up production. Purdue virologist Suresh Mittal says how long that takes depends in part on how similar the eventual vaccine is to existing ones. For instance, many drug companies are exploring the use of adenoviruses as a gene therapy for cancer. Some of the COVID-19 vaccine trials underway use adenoviruses in a similar way. If that’s a vaccine that makes it to approval, Mittal says some of the manufacturing infrastructure would already be in place.

There are additional hurdles. Many of the vaccine candidates are two-dose vaccines, given a few weeks apart. That would double the amount of vaccine needed. And along with testing vaccines’ safety and effectiveness, Mittal notes drug companies are testing how they would need to be stored — whether they would need to be refrigerated or frozen. The more precautions have to be taken to keep the vaccine usable, the more difficult distribution will be.

Once a vaccine is approved, Mittal says frontline workers like doctors and nurses, nursing home staff, and police and firefighters are likely to get priority for the first few thousand doses. He estimates it’ll take three months to have enough vaccine for a majority of people, and another three months to have the millions of doses needed to cover everyone.